in the older 2 pc rear main blocks you will find the odd one with a higher nickle content. there doesnt seem to be any ryme or reason to where they were used,I found one in a 74 blazer. yes they are far more rust resistant. I cant remember exactly but I think there is some special marking under the timing cover.
OH no an SBC debate. Back when I first started building SBC the block that everyone wanted to use was the casting numbers that ended in 010 or 020. (Ex.3970010) was the most common 4 inch bore block that's out there. It was used from the late 60's as a 302 all the way to the late 70's as a 350. It came in a 2 or a 4 bolt main. Then I read an article that explains yes the casting numbers with the 010,020 did have higher nickle content but they quit doing that in the early 70's. The only blocks that have special nickle ,tin content now are the bowtie blocks,and certain aftermarket SBC blocks...
If you care to read the article I'm referring to here is a link.
Chevy has made several alloy changes since the beginning.
Most of them have been to extend life on tooling with freerer machining alloys.
From time to time a special run of blocks was made for high stress apps.
Old time racers know the best ones.
Any four bolt with a 010 number is usually good if not core shifted.
Not all 010's are four bolts.
I have a nice one in my shop waiting for a reason to be built.
It takes about $1000-1500 in machininig to get one ready for real racing.
A heat soaked one with 100000 miles is best.
Good topic i see. Alot of various opinions though. Seems pre1971 with the 010 = tin and 020=nickle I guess a 020 block would be a good Marine app. Can anyone tell how to identify a "bowtie" block? Were bowtie only 350s or did they have 305 bowties too? or any other SBC's
this info is from the book Chev small block V8 interchange manual by David Lewis--if two numbers 10 and 20 (one over the other) are located near the camshaft bore,then ten percent tin and twenty percent nickle are present in the block, if only one number is present 10 or 20 that is the percentage of nickel. all other numbers under the timing cover are casting id
